| 摘要 |
PROBLEM TO BE SOLVED: To attain high efficiency reducing excitation current to a required minimum, when thrust is low, in an induction motor, in which the primary side and the secondary side are so disposed that they are separate from each other with a gap. SOLUTION: A magnetic flux reducing coefficient Kϕ* (magnetic flux correcting pattern), by which the reduction rate of an exciting current becomes small, when a high thrust is needed and the reduction rate becomes large, when no or a low thrust is needed is formed, based on a thrust command F* and a speed coefficient Kω* by a magnetic flux correcting pattern forming part 1. A rated excitation current IO* is corrected by the Kϕ*, and an exciting current command IO is obtained according to required thrust. In a torque current correcting part 4, the component of a rated torque current IT* is corrected by the Kϕ*, and a torque current command IT which is inversely proportional to the component of the excitation current is obtained. Component of a slip frequency ωs is obtained, based on the IO, and the IT and the induction moor is controlled based on a frequency command ωl*, which is based on the ωs and the IO and IT. |
